I can't really speak on behalf of capital punishment. In practice, it would only be acceptable if prosecutors, judges and juries never made a mistake. And Kendall's point is well taken - if the most basic function of the state is protection of the lives of its citizens, then the state is creating a contradiction by killing one of them itself, no matter what he did. (I'll ignore the implications of that statement in the abortion controversy for now.)
Assuming we're not dealing with an erroneous conviction in this particular case, how can we have this outpouring of compassion for the perpetrator, and simply forget the victim. The perpetrator (presumeably) killed someone. At least there's an argument in favor of balance. The victim (presumeably) did nothing wrong, and got killed anyway. But all the compassion is for the killer. I don't get it.
Or is the idea that the victim must have done something wrong, or the killer wouldn't have killed him?